Just to want to share my little knowledge. After mastering the chords on the guitar, learning the scales can be interesting. When you know the scales techniques, it allows you to play solos, fill-ins and lots of interesting stuff. The followings are suggested to learn :
1. The major/minor scales - need to know the scale patterns all over the fretboard for the 12 keys. Sounds difficult, but there are only 5 patterns you need.
2. Then learn the pentatonic scale - only 5 notes per pattern, also 5 patterns. Then you can play many many solos.
3. Finally learn the blues scale - add one note to the pentatonic scale, then you can play with "moods" and "emotions".
Have fun, don't stop just playing the chords.